Procedures for transporting Positron Emission Tomography (PET) Scan and Computer Assisted Tomography (CAT) Scan images from the NIH Clinical Center to the DCRT Image Processing Facility have been established. An interactive computer procedure for delineating anatomical areas of interest on a CAT scan and computing metabolic activity from the corresponding area on the related PET scan has been developed. Improved methods for establishing external coordinates to align corresponding PET and CAT scans continue to be explored.